Flanged bimetallic bearing



Jan. 26, 1965 w. H. MORRISON ETAL 3,167,404

FLANGED BIMETALLIC BEARING Original Filed Dec. 28, 1959 2 Sheets-Sheet 1 34 Wan-anus HEATING FURNACE FIG.|

CLEANING INVENTORS WILBERT H. MORRISON BY DONALD w. WILLIAMS ATTORNEY Jan. 26, 1965 w. H. MORRISON ETAL 3,167,404

FLANGED BIMETALLIC BEARING Original FilGd Dec. 28, 1959 2 Sheets-Sheet 2 /COOLING coo|.mc

FIG.3

\ 0 Z 2 Lu J 0 N o N INVENTORS WILBERT H.MORRISON DONALD W. WILLIAMS BY flJ W ATTORNEY United States Patent 3,167,404 FLANGED BIh IETALLIC BEAG Wilbert H. Morrison and Donald W. Williams, Euclid, ()hio, assignors to Clevite Corporation, Cleveland, Ohio, a corporation of Ohio Original application Dec. 28, 1959, Ser. No. 862,399, new Patent No. 3,093,885, dated June 18, 1963. Divided and this application Sept. 10, 1962, Ser. No. 222,998 3 Claims. (Cl. 29-196.2)

The present invention relates to a bimetallic strip, and is more particularly directed to the manufacture of a bimetallic strip for bearings composed of a strip of steel constituting a backing member and a layer of aluminum alloy united with one surface of the steel by means of a metallurgical bond. The composite material, thus formed, is of such a nature that it is capable of being bent and formed into various shapes without interruption of the bond between the aluminum alloy layer and the steel backing member.

This application is a division of United States Patent No. 3,093,885, issued June 18, 1963, to Wilbert H. Morrison and Donald W. Williams and assigned to the same assignee as the present invention.

The principle of this invention is applicable to a continuous type of process as well as to a batch-type operation and nothing herein is to be construed limiting the invention to a particular mode of operation.

It is of fundamental importance to have a substantial percentage of low melting point metal constituents in a bimetallic strip for superior bearing quality; this is well known. Similarly known is the difliculty to satisfactorily bond an aluminum base alloy comprising a substantial percentage of low melting point material, such as tin, to a ferrous metal. This is primarily due to the tendency of the low melting point materials to accumulate near the bonding interface. This accumulation creates a bond between the layers unsuitable for any subsequent high temperature or high load use. The aluminum base alloy, when in hot bonding contact with steel, causes a high reaction between the two metals with consequent formation of intermediate phases of steel and aluminum alloy which are positioned between the two layers and which are very brittle and tend to fracture along this plane if the composite layer is subjected to subsequent bending or forming operation. Heretofore, the bonding of aluminum alloy to a steel backing member was accomplished by utilizing a temperature above the melting point of the low melting point constituent; the subsequent application of pressure upon the composite strip led to considerable squirting and dislocation of the low melting constituents. The application of such heat upon the low melting constituents, resulted in a low strength interface which made use of the strip for fabrication into bearings virtually impossible. Bearings, particularly those used in the automotive field, are subject to extreme stresses during fabrication and subsequent use. The severe deformation during fabrication demands a strong and resilient bond.

While the interposition of a third layer of metal for instance, such as copper or nickel, has reduced some of the hereinbefore mentioned problems by allowing the application of higher temperatures and correspondingly lower pressures, the interposition of the layer has introduced numerous complicating factors in the manufacturing process.

The present invention is based on the discovery that a substantial percentage of low melting point material, e.g., tin, may be satisfactorily incorporated into an aluminum base alloy provided that the application of heat during the process does not disturb the relative location of the low melting point alloy constituents within the strip.

It is therefore the primary object of this invention to provide a method for making a bimetallic strip suitable for the manufacture of bearings and having a steel layer and an aluminum alloy layer including a substantial percentage of low melting point constituents, e.g., tin, the strip exhibiting a strong and ductile bond between the steel and aluminum layers.

It is a further object of this invention to control the application of heat to provide a strong metallurgical bond etween the aluminum alloy, comprised of a high percentage of low melting constituents, and the steel backing member, and to avoid that the low melting point constituents are pressed or squirted out during the bonding operation.

Another object of the invention is to bond aluminum alloy, containing low melting point constituents, directly to steel, without an intermediate layer to facilitate the bonding.

It is another object of this invention to provide an air-sealed chute between a furnace and preheated pressure rolls to preclude exposure of the strip to air prior to the rolling step; and to control the temperature between the furnace and the rolls so that the rolls are effective to act as controlled coolant during the rolling action.

An aspect of the invention is the method of making a bimetallic bearing which comprises selecting a layer of aluminum alloy comprising at least 5% low melting point constituents and selecting a steel backing layer, cleaning and brushing the bonding interface of the layers, passing at least one of the layers through a furnace having a controlled atmosphere and a temperature suitable to avoid dislocation of the low melting point constituents, juxtaposing the layers for heat transfer, passing said layers together through pressure rolls having a temperature between 200 to 350 F. to combine the layers face to face with each other and to effect a strong metallurgical bond therebetween, cutting the layers into sections, and deforming the sections into suitable bearing shapes.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the drawings:

FIGURE 1 diagrammatically shows a continuous process in accordance with this invention;

FIGURE 2 is a view similar to FIGURE 1, showing the aluminum alloy layer bypassing the furnace; and

FIGURE 3 is an illustration of a flanged bearing.

For carrying out the process in accordance with the invention, steel of the type commercially known as SAE 1010 has been found suitable as a steel backing member. However, the composition of the steel backing member need not be strictly in accordance with SAE 1010. For example, a cold drawn steel such as SAE 1018 may be used. A lower carbon steel is preferred since it endures a greater rolling reduction which results in an improved bond. Also, a lower carbon steel has a lower initial hardness, is less subject to cold working during cladding and forming, and is more readily stress relieved by low temperature annealing.

The composition of the carbon steels is as follows:

The aluminum alloy composition suitable for this method contains a substantial percentage of low melting bear- D I Q ing constituents, particularly tin, which is desirable for obtaining high bearing qualities. The composition may be substantially as follows:

. n i 'Percent Tii1' About 510-250 Silicon" Abbut'tlS 2.5 Copper About I5' 1.5

Nickel About 0.1-. 1.0

The remainder primarily aluminum. 1

. 4- As indicatedabove a squirting problem rolls have a surface temperature near or substantially above the melting point .of the low melting point constituents. Conversely, the use of cold,.or substantially cold rolls causes the strip to cool to such a degree so that asuitable bondingcan be longer be effected. The

' method'u'tilized herein avoids the cooling; effect of the In preparing the steel for the bonding operation'astrip V of steel sheet 10 isunwound from a coil 12 and'cleaned by means of a vapor degreaser apparatus, 14'utili zing trichloroethyle ne and passed under a wire brush apparatus 16 .until thegentire bonding surface is scratched or brushed and exhibits a rough lusterless appearance. The 'steelis passed under the :wire brush, which rotates, within a range of 1200 to 2 000 surface feet per minute, under sufficient pressureto'cut rather than burnish the steel surface.

An aluminum alloy layer 18.is simultaneously unwound from-ga coil 20, onesurface of thealuminurn alloy layer is degre'ased in a degreasing mechanism 22. and

brushed by awire brush device '24 in a manner similar as aforestated; A lighter brush pressure may be applied to scratchand roughen the aluminum: alloy layer.

The aluminum alloy layer- 18 is then attached to the steel backing member or layer 10 to insure alignment of 'the layers 33 and to prevent relative slippage thereof. This may be accomplished by drilling an opening into each layer 10, 18 at the, leading-end thereof to accom- -modate a rivet 2 6 or the like. found suitable and sufficiently strong to resist shearing forces.

A'brass rivet has been The layers; so attached are then passed through a'temperat-ure controlling furnace 28,. The speed through the furnace depends. upon the thickness of the layers. In genously bonded to the steel backing member.

eral, for a composition as described-herein" a temperature The furnace 28 isgas'tight and containsranonoxidizing atmosphere such asfan'exothermic precombusted mixture of-one part natural gas to six and one-half parts The discharge end of V the furnace is connected to a rolling mill 30,-31 by an air-tight chutje 32 to :permit transfer of the strip to rollers 30, 3-1 to prevent the formation of oxidation.

between .700.8001F. near the interface of. the strip has been found to be desirable.

*somewhat with the thickness 'of the particular layer. The

following 'arran'ge'ment'has been found to be satisfactory. Where aluminum alloy layer has a thickness within the range of .030 inch to .065 inch, it has been found that fwhen' the rolls are preheated and maintained at a temperature approximately within'the'range of 200-250 F. the preheated rolls provide the desired cooling effect.

An aluminum alloy layer having 'athickness of .065- inch to .100 inch has a correspondingly roll surface temperature approximately within the range of 225275 F.

Whenutili'zing an aluminum alloy layer having a thickness within the range of .100 inch to .150 inch an approximate temperature range of 25.0':350 F. will satisfy the requirements. v 1

By'pre-selec'ting a given strip thickness and a corresponding roll, temperature the resulting bimetallic strip is 'dimensionally'correct and is forming operation.

'In FIGUREJZ there is'illustrated a process and apparaready for the cutting and 'tussubstantially as afor'edescribed. Herein the method is modified in-thatthe aluminum alloy layer 18 bypasses ;the furnace 2'8 andenters, chute 32 near point 35. This is particularly-desirable in a continuous type of operation.

Upon reaching the predetermined, composite strip tem- I .perature, the. strip leaves the furnace andjis passed between the pressure rolls 30, 31 which are adjusted to cause a slightr'eduction in steel layer thickness and a sub-' stantial deformation in the aluminum alloy layer. More particularly, the rolls may be adjusted to establish a reduction of 2.t o 10% in;the steel layer thickness and between-20 and 40% in the aluminum alloy layer.

The rolls 30, 31 maybe preheated by a radiantrgas i burner 34,"or'other conventional means, to provide an initial-roll temperature of 200 to 350 F. During the continuous operation it may at times: ben'ecessary tocool therollslappr'eciably in orderto maintain-the proper tem- 'perature. Acold waterline 36 may supply the'cooling means'tojtherolls. The rolls are coatediwithpolloidalp graphite to prejvent bonding of the stripto the rolls.

The rolling stepitselfis of a mostcritical nature andit must be observed that the roll surface temperature is varied tosuit thefthickness'ofthealuminum alloy layer.

' critical.

The aluminum alloy layer may be brought up to the required temperature by heat transfer contact between the two metals. 1

' As shown the steel layer '10 is passed through furnace '28 and thereafter attached to the aluminum layer in preparation for-the subsequent rolling step.

In -FIGURE'3 there 'is shown a flanged bearing 38. It

* is'well known in the art that the demand. on material for a bearing of this type isappreciably greater than for other types. of bearings. The amount of low, melting polnt constituents in the soft layer -is therefore more The inclusion of 10% to 25% tin has been found to be particularly desirable' The method as describedh'ereiri produces a bondof such ductility enabling the fabrication'therefor without an inter-layer. The bearing 38 'is fabricated from'the strip 33 after it leaves the rolls' 30, 31 'and is cut intosuitable' sections. The section is then-deformed by means of a power press into 1a bearing shapq for instance into av 180 or 360 bend.

The bearing may then be worked-to provide for further The bimetallic strip upon leaving the furnace and upon entering between the rolls is relatively soft and is sensitive V 7 point constituents to be squirted out. vent such squirtin'gfaction the strip is passed between temperature controlled rolls, effecting an-instantaneous cooling of the bimetallic strip, 'whereby'the'te'mperature is reduced beloiw the melting point of'the critical constituents, and simultaneously therewith a suitable and strong'metallurgical bond is obtained;

I to pressure, which heretofore has caused the low melting In order to prej not shown herein.

refinements. The strip, 33 may be used to fabricate a bimetallic or. a trimetallic bearing. In the latter case an additionaliprecisionplate.is attached to the ,bimetal,

While 'the're have been described what at present are considered to be the preferred embodiments ofv this invention, it-will be obvious to those skilled in the art that rvarious changes and modifications may be made therein without "departing from theinvention, and it is aimed,

therefore, in the appended claims to cover all such changes and modifications as-fall within the true spirit and scope of the invention.

arises when the We claim as our invention:

1. An automotive bearing comprising: a steel backing layer and a layer of aluminum alloy metallurgically bonded to said layer face to face; said aluminum alloy layer consisting essentially of 1025% tin constituents and the balance substantially aluminum.

2. An automotive bearing comprising: a steel backing layer and a layer of aluminum alloy metallurgically bonded to said layer face to face; said aluminum alloy layer consisting essentially of 1025% tin constituents, additives selected from a group consisting of silicon, copper, and nickel, and the balance substantially aluminum.

3. An automotive bearing comprising: a steel backing layer and a layer of aluminum alloy metallurgically bonded to said layer face to face; said aluminum alloy layer consisting essentially of 1025% tin constituents, 05-25% silicon, 0.51.5% copper, 0.11.0% nickel and the balance substantially aluminum.

References Cited in the file of this patent UNITED STATES PATENTS 1,892,175 Stockfleth Dec. 27, 1932 2,373,352 Smart Apr. 10, 1945 2,586,100 Schultz Feb. 19, 1952 2,715,259 Mohler Aug. 16, 1955 2,883,739 Russell Apr. 28, 1959 2,916,337 Fike Dec. 8, 1959 2,539,246 Hensel Jan. 23. 1961 

1. AN AUTOMOTIVE BEARING COMPRISING: A STEEL BACKING LAYER AND A LAYER OF ALUMINUM ALLOY METALLURGICALLY BONDED TO SAID LAYER FACE TO FACE; SAID ALUMINUM ALLOY LAYER CONSISTING ESSENTIALLY OF 10-25% TIN CONSTITUENTS AND THE BALANCE SUBSTANTIALLY ALUMINUM. 